When stereo cameras or any other similar device is used to track an object moving through space, the tracking has not been carried out by considering the total relationship among image positions, spatial positions, and feature descriptor (e.g., brightness) of feature points on the moving object (see, for example, JP-A-10-27249(Kokai), and Tyagi et al., “Fusion of Multiple Camera Views for Kernel-Based 3D Tracking,” IEEE Workshop on Motion on Video Computing, 2007). The “image position” used herein means a position in an image coordinate system. The “spatial position” used herein means a position or disparity in a spatial coordinate system. The “disparity” used herein means the amount of discrepancy between the image positions of two points obtained by projecting a single point in space onto two images.
Since the spatial motion and the amount of change in image cannot be determined independently, the tracking has not been carried out by considering both the parameters. The “amount of change in image” means the shift in position and the change in size of a moving object observed on an image when the moving object moves through space.
Since image positions and feature descriptor are directly observed on an image, observed values contain relatively small amounts of noise. However, spatial positions are estimated, for example, based on the principle of triangulation using a plurality of TV cameras or other similar devices, so that the estimated spatial positions may contain large amounts of noise. In this case, it is difficult to calculate the spatial motion in a stable manner by using methods of related art.
As described above, no technology of related art unfortunately estimates the spatial motion of a moving object by totally considering image positions, spatial positions, and feature descriptor of feature points on the moving object. Further, when spatial positions contain noise, it is disadvantageously difficult to estimate the spatial motion in a stable manner.
The invention has been made to solve the above problems of related art, and an object of the invention is to provide a spatial motion calculation apparatus and a method for the same in which image positions, spatial positions, and feature descriptor of feature points on an object moving through space are totally considered.